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Unread 15-01-2014, 09:23
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ToddF ToddF is offline
mechanical engineer
AKA: Todd Ferrante
FRC #2363 (Triple Helix)
Team Role: Mentor
 
Join Date: Apr 2011
Rookie Year: 2011
Location: Newport News, VA
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Re: Placing a Tank after a solenoid valve

Quote:
Originally Posted by Ed Sparks View Post
I see a potential problem with this device depending on how the system is pneumatically controlled. The cylinder may be considered a second compressor if it restores the air used to push the plunger back into the storage devices when the plunger is re-cocked. In this case, I'm assuming something mechanical is re-cocking the cylinder. A solenoid valve would have exhausted the air to atmosphere in both the forward stroke and reverse stroke.
Teams implementing a system such as this need to ensure that when the cylinder is "recocked", the pressure side of the piston is vented to atmosphere. It is possible to use a winch type system to recock the mechanical latch. If the solenoid valve were in the closed position, the recocking action could raise the pressure between the cylinder and the valve over the allowable low pressure limit (or, depending on the geometry, over the high pressure limit). This could possibly cause a failure in whatever is the "weakest link" in the low pressure system.

If we go this route, we won't use a recocking mechanism that is capable of overpressurizing the low pressure side of the system. If your team does so, I would highly suggest installing a pressure relief valve set at 60psi between your solenoid and the catapult cylinder. This will help keep you legal and safe.
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